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An unusual form of constrictive pericarditis : Annular constriction

Posted Apr 22 2010 7:24am
Constrictive pericarditis(CP)  has been a fascinating disease   for the cardiologists  for many decades .  (Of course , not  so fascinating for  our  patients!) The reason why clinicians were thrilled to diagnose this entity is due to the unique clinical and echocardiographic and hemodynamic features. Further , it is  one of the few  curable forms of cardiac failure.
It is also about the  philosophy  , pericardium an inert  membrane  which is supposed to protect the heart , becomes a  villain  . When this innocuous layer  is insulted by  chronic   infection (Tuberculosis most common) , radiation injury or post cardiac surgery  it takes a dangerous avatar and  start invading   the organ which  it  guards .
The pericardium becomes thickened , (often > 5mm -2cm) calcified , behaves like a “shell of tortoise ‘ and begin to constrict the heart . Once the process of constriction sets in it becomes relentless . It only   requires   , a 10 -15mmhg of constrictive  pressure to make  the poor heart  struggle to relax .(The maximum intracardiac  diastolic pressure ,12mmhg(LV)   .For the right side of the heart it is very low (0-5mmhg) .
So it is obvious the right side of the heart RA, RV gets compressed first .This is why the classical features of constriction with edema , ascites elevated JVP occur.The associated hepatomegaly some times mimic a chronic liver disease.  Of course  relying only  on the  classical findings to diagnose CP would be a crime now .
There are many atypical varieties of CP
  • Localised constriction
  • LV>RV constriction
  • RV>LV constriction
  • Transient constriction
  • Effusive constrictive

* Rarely  constriction is confined to AV groove .  This article  is about this entity.

It is difficult to imagine how a pericardium constrict a rigid fibrous skeleton of the heart namely the AV groove.
But what happens is ,  there  are some gaps in the ring  . The  posterior mitral annulus which  has a deficient  rim  and forms  the most vulnerable  zone for pericardial constriction
Further , AV groove  is located  in a relatively  gravity dependant portion  of the heart  . It facilitates  stasis of inflammatory exudate  in this groove .This may be  the reason  why the  AV groove  shows high incidence of   calcification.
Clinical features of AV groove constriction
It mimics  a presentation of valvular heart disease.
A mid diastolic murmur across mitral valve may occur mimicking valvular MS.
Synonym : Mounsey’s pericarditis
This type of pericarditis should ideally  be called as Mounsey’s constrictive pericarditis   for his
elegant description of this entity 5o yearts ago  even before    Echocardiography was invented.
(These are the days , we struggle to diagnose Mitral stenosis without echo is a different story !)

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